The 2017 Western Australian state election was held on Saturday 11 March 2017 to elect members to the Parliament of Western Australia, including all 59 seats in the Legislative Assembly and all 36 seats in the Legislative Council. The eight-and-a-half-year two-term incumbent Liberal–WA National government, led by Premier Colin Barnett, was defeated in a landslide by the Labor opposition, led by Opposition Leader Mark McGowan.

The National Party of Australia (WA) Inc, branded The Nationals WA, is a political party in Western Australia. It is affiliated with the National Party of Australia, but maintains a separate structure and identity. Since the 2021 state election, the Nationals WA is the senior party in an opposition alliance with the WA Liberal Party in the WA Parliament. Prior to the election, the National Party was sitting in the crossbench, and the Liberal Party was the sole opposition party. The election resulted in the National Party winning more seats than the Liberal Party, and gaining official opposition status. Under the opposition alliance, the National Party leader and deputy leader would be the opposition leader and deputy opposition leader, respectively, the first since 1947, and each party would maintain their independence from each other.